im addicted to lionel's smoke fluid scent.i've used it in various mth steamer's and even after half a dozen or more refills to the mth engine the lionel smoke scent just doesn't smell right in the mth engine.
i dont think it will do any harm using it though in an mth engine.it does produce good volumes of smoke.
for me though lionel smoke fluid works and smells better in lionel engines and accessories(smoking caboose etc etc).
thop.........